I just logged in to start new thread and report my observation and this one popped up at me, which is somehow close to what I wanted to report, so replying here:
I see different behavior when connecting to the same instance of Octoprint with Windows/Chrome and Ubuntu/Chromium.
OctoPrint 1.3.10 running on OctoPi 0.16.0
Access Control: enabled
Ubuntu 18.04.2 LTS / Browser: Chromium Version 72.0.3626.121 (Official Build) Built on Ubuntu
Windows Pro 64bit / Google Chrome Version 72.0.3626.121 (Official Build) (64-bit)
Tried accessing UI by clicking on browser Favorite link and by typing in the IP address directly - the behavior is the same.
In Chromium the page loads with no data, as shown below, and in the background there are several 403 errors that cannot be seen unless you "dive into" developer tools.
If I try to click Login and enter username and password - nothing happens - I am back to the same page.
When I reload the page with CTRL-F5 the following screen appears:
And then I can log in without issues:
Under Windows OS, clicking on Favorites link or entering IP address takes directly to login dialog (3rd image in this post) and I can log in right away.
So, some kind of caching is involved when accessing from Linux platforms.
As a separate note - we are missing favicon.ico file.
This does not disturb me much as workaround is pretty simple, just wanted to share my observation.